Dr Khilan Mistry asked 46-year-old Allum not to threaten him and told him to leave after he stuck his middle finger up and abused staff behind the receptionist desk.

Violent Richard Allum launched an attack on his Sheerness doctor

The GP was punched in the face as he went to walk away from Allum - and was hit on the left cheek, but did not suffer any lasting injury.

Allum was wrestled to the ground by patients in the waiting room and ejected from the building.

He then went to a friend's nearby home to get a claw hammer and tried to get back into the building, but staff had locked the doors.

Former drug user Allum has lived in a flat above the surgery for the past eight years.

He admitted affray when he appeared at Maidstone Crown Court by TV link with Elmley Prison.

"He couldn't track down where his medication was and he simply lost it. He fully accepts he should not have reacted in the away he did..." - Mary Jacobson, defending

He denied possessing an offensive weapon, a claw hammer, and the charge was left on the court file.

The court heard he had only used the hammer to get back into his flat after the incident as he had locked himself out.

Judge Charles Macdonald QC also heard that, when he was arrested and taken into custody, Allum urinated in front of police officers at the custody desk.

He also admitted being in breach of a 12-month conditional discharge he had been given in August last year for two shoplifting offences.

Mary Jacobson, defending, told the court Allum had lost his temper as he "really needed his pain relief" after going though a series of operations on his leg, having suffered serious injuries during a crash three years ago.

She added: "He couldn't track down where his medication was and he simply lost it. He fully accepts he should not have reacted in the away he did."

Judge Macdonald also heard Allum had 42 previous convictions for carrying out 114 offences, including theft, assault and drug convictions.

Allum was jailed for 12 months. He received no separate penalty for the breach of conditional discharge.